Monthly Archives: November 2010

Nissan Leaf MPG Numbers Very Flawed

Cross-posted from Coyote Blog

The EPA has done the fuel economy rating for the all-electric Nissan Leaf.  I see two major problems with it, but first, here is the window sticker, from this article

Problem #1:  Greenhouse gas estimate is a total crock.  Zero?

The Greenhouse gas rating, in the bottom right corner, is that the car produces ZERO greenhouse gasses.  While I suppose this is technically true, it is wildly misleading.  In almost every case, the production of the electricity to charge the car does create greenhouse gasses.  One might argue the answer is zero in the Pacific Northwest where most power is hydro, but even in heavy hydro/nuclear areas, the incremental marginal demand is typically picked up by natural gas turbines.  And in the Midwest, the Leaf will basically be coal powered, and studies have shown it to create potentially more CO2 than burning gasoline.  I understand that this metric is hard, because it depends on where you are and even what time of day you charge the car, but the EPA in all this complexity chose to use the one number – zero – that is least likely to be the correct answer.

Problems #2:  Apples and oranges comparison of electricity and gasoline.

To understand the problem, look at the methodology:

So, how does the EPA calculate mpg for an electric car? Nissan’s presser says the EPA uses a formula where 33.7 kWhs are equivalent to one gallon of gasoline energy

To get 33.7 kWhs to one gallon, they have basically done a conversion through BTUs — ie 1 KWh = 3412 BTU and one gallon of gasoline releases 115,000 BTU of energy in combustion.

Am I the only one that sees the problem?  They are comparing apples and oranges.  The gasoline number is a potential energy number — which given inefficiencies (not to mention the second law of thermodynamics) we can never fully capture as useful work out of the fuel.  They are measuring the potential energy in the gasoline before we start to try to convert it to a useful form.  However, with electricity, they are measuring the energy after we have already done much of this conversion and suffered most of the losses.

They are therefore giving the electric vehicle a huge break.  When we measure mpg on a traditional car, the efficiency takes a hit due to conversion efficiencies and heat losses in combustion.  The same thing happens when we generate electricity, but the electric car in this measurement is not being saddled with these losses while the traditional car does have to bear these costs.  Measuring how efficient the Leaf is at using electricity from an electric outlet is roughly equivalent to measuring how efficient my car is at using the energy in the drive shaft.

An apples to apples comparison would compare the traditional car’s MPG with the Leaf’s miles per gallon of gasoline (or gasoline equivalent) that would have to be burned to generate the electricity it uses.  Even if a power plant were operating at 50% efficiency (which I think is actually high and ignores transmission losses) this reduces the Leaf’s MPG down to 50, which is good but in line with several very efficient traditional cars.

Lindzen Testimony

I wanted to link to Richard Lindzen’s Congressional testimony.  For slides, they are pretty easy to follow as they are mostly text.  I want to particularly point out slide 4, which I think on one page outlines the single most important point to understand about anthropogenic global warming theory.  When given just one minute to discuss climate, this slide embodies the message I give.

Here are two statements that are completely agreed on by the IPCC. It is crucial to be aware of their implications.

1. A doubling of CO2, by itself, contributes only about 1C to greenhouse warming. All models project more warming, because, within models, there are positive feedbacks from water vapor and clouds, and these feedbacks are considered by the IPCC to be uncertain.

2. If one assumes all warming over the past century is due to anthropogenic greenhouse forcing, then the derived sensitivity of the climate to a doubling of CO2is less than 1C. The higher sensitivity of existing models is made consistent with observed warming by invoking unknown additional negative forcings from aerosols and solar variability as arbitrary adjustments.

Given the above, the notion that alarmingwarming is ‘settled science’ should be offensive to any sentient individual, though to be sure, the above is hardly emphasized by the IPCC. 4

“No Disagreement Whatsoever”

I continue to be fascinated by the parallels between economic and climate science and their internal debates.  Both sciences study horrendously complex systems where controlled studies to parse cause and effect are difficult if not impossible to structure.  And both seem to have the same pressures towards politicization, with very similar results.  With a few words changed, this could easily have been written by a climate skeptic about any number of Mann/Hansen/et. al. statements:

Mr. James Fallows
National Correspondent, The Atlantic

Dear Mr. Fallows:

This afternoon on National Public Radio you proclaimed that “there is essentially no disagreement whatsoever” among economists that more stimulus spending is necessary today [emphasis in the original].

You are misinformed.

Last year, hundreds of economists signed a petition, circulated by the Cato Institute, whose key clause reads “it is a triumph of hope over experience to believe that more government spending will help the U.S. today.”  Among the economists who signed this petition in opposition to ‘stimulus’ spending are three Nobel laureates in economics (Edward Prescott, Vernon Smith, and my colleague James Buchanan).  Others signers include Chicago’s Eugene Fama and Sam Peltzman, Harvard’s Jeffrey Miron, Texas A&M’s Thomas Saving, Cornell’s Rick Geddes and Dean Lillard, University of Virginia’s Lee Coppock and Kenneth Elzinga, Duke’s Michael Munger and Edward Tower, University of Rochester’s Mark Bils and Ronald Schmidt, Rutger’s Michael Bordo and Leo Troy, University of Southern California’s John Matsusaka and Kevin Murphy, and one of the world’s preeminent scholars of money and banking, Carnegie-Mellon’s Allan Meltzer.

Perhaps these economists and the many others who’ve signed this petition (including myself) – and who continue to speak out against what we believe to be the folly of ‘stimulus’ – are mistaken.  But for you to announce publicly that there is “no disagreement whatsoever” among economists that more stimulus spending is desirable is so wildly inaccurate that it borders on being irresponsible.

Donald J. Boudreaux
Professor of Economics
George Mason University
Fairfax, VA 22030

I compared macroeconomic and climate models in my Forbes column here.